Introduction to the Special Issue on the Development of People With Down Syndrome Throughout the Lifespan (Part 2).

03Original abstract

In the last issue we outlined the rationale for this special issue on Down syndrome, which has been spread out over two issues. Briefly, advances in basic science with Down syndrome mouse models have led to promising neurotransmitter and neurochemical targets for intervention. However, translating this basic science to clinical trials in individuals with Down syndrome has not yet been successful. Challenges with quantifying the Down syndrome behavioral phenotype, their developmental profile, and treatment outcome measurement need to be addressed in translational research for individuals with Down syndrome. The Eunice Kennedy Shriver National Institute on Child Health and Human Development (NICHD) coordinated meetings of experts in Down syndrome to address these challenges in the research on outcome measures for clinical trials in Down syndrome. This group identified the need for a special issue on Down syndrome to describe their behavioral phenotype and the refinement of clinical outcome measures. The call for submissions for the special issue stated our focus "on manuscripts that contribute to our current understanding of cognition, language and communication, self-regulation, and social-emotional functioning in Down syndrome across the lifespan, from early childhood through to older adulthood." The first issue focused on articles related to cognition and executive functioning. The current issue focuses on articles related to language, hearing, communication, and academic skills.Evaluating the development of language in youth with Down syndrome using longitudinal designs informs our understanding of developmental trajectories and the rate of skills acquisition. Lee et al.'s article, "A Multi-Method Investigation of Pragmatic Development in Individuals With Down Syndrome," describes a longitudinal evaluation of pragmatic language in school-age children with Down syndrome. They document the rate of pragmatic language development in a sample of youth with Down syndrome in comparison to a typically developing comparison group. Their work also demonstrates the need to account for gender in measurement work, as they identified gender differences in pragmatic language skills, but not gender differences that diverge over time. Their findings highlight specific types of pragmatic language violations that have implications for intervention work. In addition, this study demonstrates the overlap between constructs assessed as primary outcome measures, particularly the overlap between constructs of language and executive functioning. These findings have implications for the selection of primary outcome measures for clinical trials.Feasibility studies are a necessary component of developing clinical interventions. These studies support the refinement of treatment dosage, study design, selection of outcome measures and the realistic capability of conducting a clinical trial. Finestack et al.'s article, "The Evaluation of a Personal Narrative Language Intervention for School-Age Children With Down Syndrome," examines the feasibility of a language intervention and reports treatment gains in micro- and macro-structural language measures and generalizability of gains for their pilot sample. This feasibility study also provides important insights for future clinical trials with this population, including the importance of using visual supports, extending the length of baseline sessions, and ensuring salient events are selected for personal narrative interventions.In addition to assessing cognitive and language outcomes, the measurement of physical health is important both as an outcome measure and as a potential confound in the design of clinical trials. Pasqualina et al.'s article, "Audiologic Assessment in Adults With Down Syndrome," highlights the prevalence of hearing loss in adults with Down syndrome. Using a national sample, they replicated findings of high rates of hearing loss that increase with age in adults with Down syndrome. Their findings have clinical implication for health care guidelines, screening for hearing in adulthood, and the need for preventative strategies and interventions to support the hearing of adults with Down syndrome. Their findings also have implications for the selection and administration of clinical outcome measures during a clinical trial to ensure participants can hear the instructions and perform tasks appropriately.Technology can be used to improve our precision in measuring clinical outcomes. Tsao et al.'s article, "Handwriting in Children and Adults With Down Syndrome: Developmental Delay or Specific Features?," demonstrates how writing on a graphic tablet can be used to assess multiple components involved in the motor task of handwriting, including stroke length; stroke duration; and handwriting speed, pauses, and duration. Their work has implications for how we refine our measures, possibly with the aid of technology, for use in future clinical trials.This special issue features research efforts designed to better understand the functioning of individuals with Down syndrome across the lifespan. The articles included across the two issues demonstrate that current research continues to refine measurement (e.g., Edgin, Esbensen, Tsao), evaluate changes longitudinally and cross-sectionally (e.g., Gilmore, Lee, Pasqualina,), and pilot treatment interventions (e.g., Finestack). This research on the development of individuals with Down syndrome (and ongoing research not featured in this special issue) is promising and needed. This type of rigorous science will inform treatment and clinical outcome research in order to support the development of positive outcomes for individuals with Down syndrome.

American journal on intellectual and developmental disabilities, 2017 · doi:10.1352/1944-7558-122.4.287